i believe i connected mine to my fog lamp circuit. So when ever the marker lights are on, the circuit juiced. I did it 4 years ago, so i don't remember very well, but i will be doing another kit soon on my new car. Oh, yeah the relays go out often sometimes, i am on my 3rd. The 3rd one has lasted 2 years. first one was dead out of box, second one lasted for about a year. Really annoying!